Wireless communication systems deliver various services to mobile users which are separated from the fixed telecommunications infrastructure. These wireless systems employ radio transmissions to interconnect mobile user devices with base stations in a wireless communication network, often in a cellular geometry. The base stations, in turn, are connected to mobile switching centers which route connections to and from the mobile user devices to other users on different communications networks such as the public switched telephony network (PSTN), Internet, etc. In this manner, users that are away from fixed sites or are on the move may receive a variety of communication services such as voice telephony, paging, messaging, email, data transfers, video, Web browsing, etc.
Since the wireless interconnections between base stations and the mobile users employ radio frequencies, wireless users must use common communication protocols set to share the scarce radio spectrum allocated for wireless communication services. One important protocol relates to the access method used to connect a mobile user device to the wireless communications network. Various access methods include frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and orthogonal frequency division multiplex (OFDM). OFDM is increasingly popular in terrestrial wireless communication systems because its multicarrier format facilitates compensation of multipath distortions. OFDM utilizes a plurality of carriers spaced apart in the frequency domain such that data modulated on each carrier is orthogonal (and thus independent) to the others. OFDM has the advantage of being conveniently modulated and demodulated through very efficient Fast Fourier Transform (FFT) techniques in both the transmitter and receiver.